You should check out www.Viewbug.com. It has various memberships including a free option. They have theme-based contests that you can enter (!20 at any given time). And you get a fair amount of feedback.

All of my photos that I post are on Flickr. Only a few are on 500px, but that's only because I don't want to post in several different places. I post my extra favorites to 500px for more exposure, but even then its few and far between.

I recently read that there is quite a community on Google+ of all places.

I'm also of the opinion that Flickr is better for putting up sets of photos (family vacations, photoshoot samples, etc). I have not interacted too much with the Flickr community so I can't comment on how constructive the criticism is.

I recently started posting on 500px (http://500px.com/VasilisArgyropoulos) and although the vast majority of comments/votes/"faves" are made with an anticipation of a reciprocal vote, I have received enough honest feedback that it has helped me improve my skills. I am not crazy about the anonymous "dislikes" since I have seen amazing photos getting flagged with dislikes just so that their scores would lower and bump the photo down the ranks.

I'm not sure why you've chosen vk.com, as its main audience is Russian-speaking, and most of registered people are teenagers. The reason it works for me is that I live in the area and I'm a wedding photographer, so it's about time for some of them to get marry

I believe that every photography-related community has specific photography segment that it may be mainly specialized at. So it's up to us to identify what fits our needs

I'm not sure why you've chosen vk.com, as its main audience is Russian-speaking, and most of registered people are teenagers. The reason it works for me is that I live in the area and I'm a wedding photographer, so it's about time for some of them to get marry

I believe that every photography-related community has specific photography segment that it may be mainly specialized at. So it's up to us to identify what fits our needs

Simple, my girlfriend is from Ukraine (ZP)VK has a great English translation so language isn't a problem and the site in general is light years better (for our taste) than fb.

Not sure about that user info.. according to their data: AudienceOver 190 million users are registered on the site.Around 2 500 000 000 pages are opened daily (LiveInternet).Around 67% of visitors live in Russia (LiveInternet).More than 70% of users are over 25 years old (comScore).

Simple, my girlfriend is from Ukraine (ZP)VK has a great English translation so language isn't a problem and the site in general is light years better (for our taste) than fb.

Not sure about that user info.. according to their data: AudienceOver 190 million users are registered on the site.Around 2 500 000 000 pages are opened daily (LiveInternet).Around 67% of visitors live in Russia (LiveInternet).More than 70% of users are over 25 years old (comScore).

Love your work.

We're from DP, 2 hours away

As for VK, I feel that people over 25 don't visit the web-site that often, compared to younger people. Audience is interested in something extraordinary these days, so to please them pictures should really stand out of the crowd.

We've got interesting results during this year wedding season, so I'll add you to my friends list in VK to share those as soon as we have time to upload them

You have very nice works too, but I believe there's always room for personal growth

P.S. I didn't get the percentage of >25 years old correctly from the first sight, because my eyes just didn't believe that. I don't think that's true even now. My personal feeling says the visitors core is in the 17-25 years range.